Fix a possible crash when uploading firmware files using libdfu
Fix a possible crash when uploading firmware files using libdfu

hughsie/fwupd,vathpela/fwupd,hughsie/fwupd,vathpela/fwupd,hughsie/fwupd,fwupd/fwupd,fwupd/fwupd,fwupd/fwupd,vathpela/fwupd,superm1/fwupd,fwupd/fwupd,superm1/fwupd,superm1/fwupd,vathpela/fwupd,hughsie/fwupd